Assessment of soil nutrient utilization for jasmine rice using geographic information systems in tung kula rong hai area

Tung Kula Rong Hai is mostly sandy soil, lack of plant nutrients, flooding in some areas, water shortage of the growing season, flooding end of season and rainless in dry season, soil is spreading salinity, farmers lack motivation to improve the soil and the use of technology to increase crop yields. As a result, some areas of Tung Kula Rong Hai used to grow rice have reduced yield problems and low quality rice makes the aroma decrease. This problem is due to the fact that available of soil nutrients have decreased, especially nitrogen, phosphorus and potassium. This will affect the yield and quality of rice in terms of aroma, softness, toughness, etc. Therefore, the study on the usefulness of soil nutrients in Tung Kula Rong Hai area is important. The results of this study showed that the almost of area, total N content in the soil was found to be in the medium level of 0.02-0.04%, soil pH will have a moderate was >5.0-5.5, available phosphorus is low 10 mg/kg, potassium in soil is low 4-15 mg/kg, etc. The study suggests that to cultivate rice quality and high yield are need to have the quantity of nutrients in the soil, and soil pH that is appropriate such as nitrogen must be higher than 0.04%, available phosphorus must be greater than 25 mg/kg and available potassium higher than 50 mg/kg. It also requires soil pH suitable for rice planting is in the range of 5.0-6.5, etc. The results of this study suggest that almost of Tung Kula Rong Hai area will be available of soil nutrients are relatively low is 45.80% of total area, this may be due to the soil contain available phosphorus and potassium in low-threshold, mostly which may be caused by a runoff and leaching of various nutrients in the soil loss during the rainy season.